A Template for a javascript library, with some utilities included

libaryTemplate.js

/* Copyright (c) 2016 Jeffrey Meng | MIT License
 * Partially taken from http://checkman.io/blog/creating-a-javascript-library/ and/or youmightnotneedjquery.com
 */
(function(window) {
  'use strict';

  function define_Library() {
      //UTILS
      var throwError = function(txt, type) {
          //throws an error
          var type = " " + type + " " || " ";
          var e = new Error(txt);
          e.name = 'Libary' + type + 'Error';
          throw e;
        }
        //get's an object and adds some utils to the wrapper. Sort of like jquery, but a lot fewer functions.(delete it if you want)
        //some functions in this utility function is taken from youmightnotneedjquery.com
      var /* $ = */ getElement = function(selector) {
        var wrapper = document.querySelector(selector);
        // get Dom wrapper.
        //function to add custom functions to the wrapper.
        this.addFunction = function(name, code) {
          // if code is undefined, assume name is an object with name:function pairs
          if (!code) {
            for (var key in name) {
              //check is item is not a prototype
              if (name.hasOwnProperty(key)) {
                var value = name[key];
                //set function name in the wrapper to the value(function code)
                wrapper[key] = value;
              }
            }
          }
          //there is only one function being defined. Set the name to the function(code)
          else {
            wrapper[name] = code;
          }
        };
        //add utility functions(you can add more functions or delete some to suit what you need for your libary)
        this.addFunction({
          //returns or modifies the value of an input or textarea field
          "val": function(val) {
            //if val is undefined, assume we want to read it and return the value
            if (val === null) {
              return this.value;
            }
            //else set the value to val
            else {
              this.value = val;
            }
          },
          //returns the html string of an element.
          "html": function(val) {
            //if html is undefined, assume we want to read it and return the html
            if (!val) {
              return this.innerHTML;
            }
            //else set the value to html
            else {
              this.innerHTML = val;
            }
          },
          // class functions: adds or removes a class. 
          "addClass": function(className) {
            if (this.classList) this.classList.add(className);
            else this.className += ' ' + className;
          },
          "hasClass": function(className) {
            if (this.classList) return this.classList.contains(
              className);
            else return new RegExp('^| ' + className + ' |$', 'gi').test(
              this.className);
          },
          "removeClass": function(className) {
            if (this.classList) {
              this.classList.remove(className);
            } else {
              this.className = this.className.replace(new RegExp(
                "(^|\\s+)" + className + "(\\s+|$)"), ' ');
            }
          },
          //event handler
          "on": function(event, handler) {
            if (this.addEventListener) {
              this.addEventListener(event, handler);
            } else {
              this.attachEvent('on' + event, function() {
                handler.call(this);
              });
            }
          },
          //hides an element
          "hide": function() {
            this.style.display = 'none';
          },
          //shows an element
          "show": function() {
            this.style.display = 'block';
          },
          "keyup": function(handler) {
            return this.on("keyup", handler);
          }
        });
        return wrapper;
      };
      // end of UTILS
      var Library = {};
      Library.about = {
        version:1.0,
        author:"Your Name",
        //etc.
      }
      Libary.version = Libary.about.version;
      Libary.author = Libary.about.author;

      Library.myFunction = function() {
        //do stuff
      }
      return Library;
    }
    //define globally if it doesn't already exist
  if (typeof(Library) === 'undefined') {
    window.Library = define_Library();
  } else {
    var e = new Error("The Library was already defined. Please rename all variables with the name 'Library'.");
    e.name = 'Library Inclusion Error';
    throw e;
  }
  })(window);